Doctor for paper-making and like machines



June 6, 1933. F w -v c 1,912,605

DOCTOR FOR PAPER MAKING AND LIKE MACHINES Filed June 15, 1931 2 Sheets-Sheet 1' F192. a s 7 4 A ma/70R. Jaw/MM wa & a Zfl/l/ June 6, 1933. F. w. VICKERY V DOCTOR FOR PAPER MAKING AND LIKE MACHINES Filed June 13, 1951 2 SheetsQ-Sheet 2 Patented June 6, 1933 UNITED STATES FREDERIGK PATENT ouron WILLIAM VIGKERY, or 'Lonnon, ENGLAND, AssIonon. 'ro vrcxnny mconronarnn, a oonrona'rron or mssacnusn'rrs DOCTOR IFOIB- PAIER- MKING AND LIKE MACHINES Application filed June 13, 1931, Serial No. 544,119, and in Great Britain July 31, 1930.

This invention relates to doctors for the.

rolls of pa 'er-inaking and like machines and particu arly to the fastening of their blades. In the older forms of doctor the 5 blade is fastened directly upon a'rigid carrier mounted in the machine frame.- In modern doctors the blade is commonly slid endwise into a slot or groove in a support, and is. pressed upon the rollby resilient 1 means which may constitute the support or may be additional. to it. By these constructions the blade is enabled to bend lengthwise throughout its width, and so its edge can Y maintain an even pressure on the roll not- 1 withstanding irregularities in the roll or movements of it relatively to the doctor carrier. Only at the ends is there any means for retaining the blade in its slot, and consequently it is liable to spring out of posiforce. Q

One purpose of this invention is to secure the blade against such dislodgement from its support, even under excessive working pressure, without diminishing the flexibility attained by modern constructions. A further purpose of theinvention is to enable the blade to be safely removed and replaced while the paper-makingmachine is running.

With these ends in view the invention provides .for attaching the blade to its support by means of enlargements or rojections in the thickness of the blade 10 god in an undercut slot in the support from which 86 they can be disengaged only by' endwise 1 movement. Such enlargements or projections mustbe of small dimensions especially in the lengthwise direction of the blade in order that they may notinterfere with the 40 bendin of the blade; As t eblade is often made of tempered steel it is best to attach separaterenlargements to it; a convenient method is to fasten studs in pairs at intervals along the rear edge of theblade, one stud of each pair be- .ing on one side and one on the other.

The use of such an attachment excludes the possibility of the blade being dislodged b undue pressure. Moreover it'enables the blade to be removed and replaced without tion if it is pressed upon the roll with undue danger while the paperunaking machine is running. The same method of attachment may be applied in some cases to the resilient means which press the doctor blade upon the roll, so'that these, too, can be interchanged 56 without stopping the machine.

Examples of constructions embodying the invention -'are shown in the accompanying drawings.

Figure 1 is a transverse section of a doc- 00' tor in which the blade is carried in spring fingers, substantially as has been described in my former Patent No. 1,552,363.

Figure 2 is a similar view of a modification in which stifi fingers yieldably con 05 nected with the carrier are employed.

Figure 3 is an edge View of a blade show-. ing a preferred form of enlargements or projections.

Figure 4 is an edge view of the slotted '70 supports. v

Figures 5, 6 and 7 are transverse sections of constructions in which both the blade and the resilient means by which it is' pressed upon the roll are held in the support by pro- .yections engaging in undercut slots.

In" Figure 1 the blade 1 is carried upon a spring plate or a number of spring fingers 2 as described in my "former patent'above mentioned. But instead of the -rear edge so of the blade being received in a simple slot or groove between the spring fi'n er and the head of-a stud secured in the nger, it is fitted with projections or enlargements 3 which are received in an undercut slot 4 formed in a support or holder 5 attached to .the spring finger. A bar of the section shown may readily be produced by extrusion and cut into suitable lengths; these are fastenedone to each finger if the resilient suponport consists of spring fingers, or are spaced apart along the edge of the spring plate if the support is a single plate. Preferably the slot 4 presents a rear ledge 6 on which the rear edge of the blade rests. Figure 2 is a similar view of a modification in which the holder 51 includes a. stilf 'finger portion 7 resiliently supported from the doctor carrier 8 by a spring plate9 'or a series of spring fingers.

mouth 10 of the slot 4, so that the blade cannot snap out of. the holder whatever pressure is applied to it, but can only be withdrawn lengthwise when the doctor has been lifted from the roll. If the holders 5 or 7 are spaced apart and the pairs of rivets 3 are correspondingly spaced it is not necessary to move the blade lengthwise a distance equal to its length in order to withdraw it; it may be moved lengthwise sufiiciently to disengage each pair of rivets from the holder in which it lies, and then removed in the direction of its width. In this case means, such as are already known, must be provided to prevent any considerable lengthwise movement of the blade during working. If it is preferred that the blade should be removable only by complete lengthwise withdrawal, the pairs of rivets 3 are so spaced that when one registers with a gap between the fingers and is therefore free, a'

neighbouring slotted -,holder.

In such an arrangement, or if the holders pair is still engaged in a 7' are in close proximity, as indicated in the edge view of them in Figure 4, so that the blade must be inserted and removed wholly by lengthwise movement, it 'is desirable to provide means, such as'the studs 11 at the edge of each finger overlapping the next, to prevent undue displacement of one finger with respect to the other; and it is also desirable to flare the ends 12 of the mouth 10 of the undercut slot, so that these still overlap when neighbouring fingers lha-ve the' maximum relative displacement'allowed by the studs 11. These means ensure that a blade thrust in from one end will findits way through the undercut slot from finger to finger and not be stopped by abutting against a displaced finger.

Figure-'5 shows a construction in which not only the blade but also the resilient means by which it is pressed upon the roll,

. are held in the manner above described. The

extruded bar 15 forming the support is attached directly to the carrier 22. In it are two undercut slots 4, 16, the latter lying above and in'the rear ofthe former in position to receive a spring plate 17 (or a series I of spring fingers) whlch bearsupon the blade 1 and is-retained in the slot 16 by enlargements 18. These may in this case be continuous bars, but preferably are rivets asi already described. It will be seen that the mouth 10 of the slot 4 limits the extent to which the blade 1 can be deflected, and so hinders the spring 17 being overstrained. I

Should the spring, however, become per-- manently deformed it can be removed and inserted the reverse way, or replaced by another while the machine is working.

.pressed upwards sufliciently to release the projections 3. Thus in this case the projections 3 do not alone wholly perform the function of retaining the blade but with the rear edge of the blade they constitute an enlargement which is confined within a somewhat morecomplex form of undercut slot made up of the principal slot 4 and the groove 23.

Figure 7 shows a construction like that of Figure 5 for use Where the resilient means pressing the blade upon the roll consists of a strip of rubber 19. This strip can also be made by extrusion, and is formed with a narrow neck QOland an enlargement 21 to be retained in the slot 16.

I claim:

1. In a doctor the combination of a renewable blade, resilient means for supporting said blade while permitting it to bend .throughout its width, said means being formed with an undercut slot, and thickenings in said bladeof small dimension in its lengthwise direction adapted to enter said undercut slot by lengthwise movement but not releasable by movement at right angles.

2. A renewable blade for doctors comprising a flexible strip having projections in its thickness of small lengthwise dimension spaced at intervals along its length.

3. A renewable blade for doctors comprising a flexible strip, and pairs of rivets spaced at intervals along its length, the rivets of a pair having their heads on opposite sides of theblade.

' 4. In a doctor, a blade support comprising a number of resiliently yielding fingers presenting at their ends aligned undercut slots flared at their ends, and means for limiting the relative movement of said fingers to the width of the flare. I

5. In a doctor the combination of a blade, a blade support having an undercut slot therein, a resilient plate, an enlargement upon one edge of said plateadapted to engage 11 said undercut slot so as to be removable only by endwise movement .while the other edge of said plate bears on said blade.

'6. In a doctor the combination of a support .having two undercut slots therein, a bladehaving enlar ements thereon adapted to engage in one 0 said undercut slots and to be releasable only b endwise movement, and a resilient plate aving enlargements thereon adapted similarly to engage in the other undercut slot while the plate bears upon theblade.

7. In a doctor the combination of a blade carrying projections, a support having an undercut slot to receive the edge ofsaid blade and its projections and to limit the yield of said blade, and resilient means attached to said support and bearing upon said blade.

8 In a doctor, a blade support comprising go a resiliently yielding'member with a series of short holders attached thereto presenting at its edge aligned undercut slots.

9, In a doctor, a blade support comprising a number of resiliently yielding fingers with short holders attached to individual fingers presenting at their ends aligned undercut slots.

10. In a doctor the combination of a blade carrying projections, a support having an 10 undercut slot to receive and retain the edge of saidblade and its projections, and resilient means attached to said support and bearing upon said blade.

In testimony whereof I have. signed-my name to this specification. v

FREDERICK WILLIAM VIOKERY. 

